code: def test_flatten_hss_setting(self) -> None:
      t = Cast(search_space=self.hss, observations=[])
      self.assertTrue(t.flatten_hss)
      t = Cast(
          search_space=self.hss,
          config={"flatten_hss": False},
          observations=[],
      )
      self.assertFalse(t.flatten_hss)
      self.assertFalse(self.t.flatten_hss)  # `self.t` does not have HSS
      self.assertTrue(self.t_hss.flatten_hss)
  
file_path: Ax/ax/modelbridge/transforms/tests/test_cast_transform.py
imports: from copy import deepcopy
  from unittest.mock import patch
  from ax.core.observation import ObservationFeatures
  from ax.core.parameter import ChoiceParameter, FixedParameter, ParameterType, RangeParameter
  from ax.core.search_space import HierarchicalSearchSpace, SearchSpace
  from ax.modelbridge.transforms.cast import Cast
  from ax.utils.common.constants import Keys
  from ax.utils.common.testutils import TestCase
  from ax.utils.testing.core_stubs import get_hierarchical_search_space
label_desc: Use image node_id 4 for calling the CastTransformTest obj's underlying member method code with example usage: obj.test_flatten_hss_setting() without return types